Golf ball and golf ball mold

ABSTRACT

The invention provides a golf ball manufactured using a mold having a top half and a bottom half, which ball has formed on a surface thereof, near a seam line corresponding to a parting line between the top and bottom halves of the mold, a recessed and/or raised mark serving as an indicator for detecting the direction or position of the seam line. The invention also provides a golf ball mold composed of a top half and a bottom half that detachably join together so as to form therein a spherical cavity into which a material is injected to mold a golf ball, which mold bears, near a parting line between the top and bottom halves on a wall of the cavity, a raised or recessed feature for forming a mark as an indicator for detecting the direction or position of the parting line. The invention enables the direction and position of the seam line on the surface of the ball to be easily identified and enables the subsequent steps of visually inspecting the ball and applying indicia to the surface of the ball to be carried out more smoothly and advantageously, making it possible in particular to greatly shorten the time devoted to these operations.

CROSS-REFERENCE TO RELATED APPLICATION

This is a divisional of U.S. application Ser. No. 11/392,586, filed Mar.30, 2006. The entire disclosure of the prior application is incorporatedby reference herein.

BACKGROUND OF THE INVENTION

The present invention relates to golf balls, such as one-piece golfballs, solid golf balls composed of a core enclosed by one or more coverlayer, and thread-wound golf balls. The invention also relates to moldsfor molding such golf balls.

Horizontally separating two-part molds have hitherto been used as moldsfor injection molding a cover resin material over a core in themanufacture of golf balls. When such a two-part mold is used, a seamline corresponding to the parting line of the mold appears on the golfball.

This seam line is convenient for visually inspecting the golf ball andfor applying indicia to the ball. For example, flash normally forms atthe seam line corresponding to the parting line of the two-part mold. Byplacing the ball in a buffing apparatus so that the seam line prior todeflashing is centrally positioned, buffing can be efficiently carriedout. It is thus important to know where the seam line is located, and toposition the ball accordingly.

When an indicia such as lettering, a design or a trade mark is appliedonto the seam line of a golf ball, it is essential to know the positionof the seam line beforehand.

However, to improve the aerodynamic properties and increase the distanceof travel in recent golf balls, and to make the arrangement of dimplesformed on the surface of the ball as dense and uniform as possible, ithas become common practice to place a plurality of dimples across theparting line. This has made it impossible to clearly distinguish, as abelt, the seam line on the surface of the ball which is left when theball is molded in a two-part mold and which corresponds to the partingline of the mold. As a result, in subsequent steps, it has beendifficult to smoothly and efficiently carry out such operations asvisual inspection of the golf ball and the application of indicia atspecific positions.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a golfball having on the surface thereof a seam line the position anddirection of which can be easily distinguished, enabling work in thesubsequent operations of visually inspecting the ball and applyingindicia to the surface of the ball to be carried out smoothly andadvantageously. Another object of the invention is to provide a mold formanufacturing such a golf ball.

Accordingly, in a first aspect, the invention provides a golf ballmanufactured using a mold having a top half and a bottom half, whichball has formed on a surface thereof, near a seam line corresponding toa parting line between the top and bottom halves of the mold, a recessedand/or raised mark serving as an indicator for detecting the directionor position of the seam line.

Preferred embodiments of the golf ball of the invention include I to IXbelow, in which:

I. The golf ball has one or more mark on top and bottom portions of theball on either side of the seam line;II. If the seam line represents 0° latitude, the mark is disposed on thegolf ball surface within a range in latitude of 1° to 45°;III. The golf ball is divided into two hemispheres by the seam line,wherein marks on the respective hemispheres are disposed so as to besubstantially equally spaced apart relative to an axis of rotationcircumscribed by the seam line;IV. The golf ball is divided into a first and a second hemisphere by theseam line, wherein marks on the first hemisphere exist in a relativearrangement with marks on the second hemisphere such that the marks onthe first hemisphere are separated from the marks on the secondhemisphere at a given angle of from 20° to 40° relative to an axis ofrotation circumscribed by the seam line;V. The mark is formed on a surface of a dimple and/or land area on theball;VI. The mark is composed of one simple symbol;VII. The mark has a size of at most 4.0 mm by 4.0 mm;VIII. The mark has a height or depth of 5 to 200 μm;IX. A raised mark is formed within a dimple on the surface of the balland has a height set so that the mark does not extend above an edge ofthe dimple.

To achieve the above objects of the invention, the invention provides,in a second aspect, a golf ball mold having a top half and a bottom halfthat detachably join together so as to form therein a spherical cavityinto which a material is injected to mold a golf ball, which mold bears,near a parting line between the top and bottom halves on a wall of thecavity, a raised or recessed feature for forming a mark as an indicatorfor detecting the direction or position of the parting line.

In the golf ball and the golf ball mold of the invention, by having themold bear a mark-forming raised or recessed feature near a parting linebetween the top and bottom halves that detachably join together to forma spherical cavity, and on the wall of the spherical cavity, a recessedand/or raised mark can be formed on the surface of the molded ball.Moreover, by placing this mark near the seam line on the surface of theball, the mark can be quickly recognized, enabling the direction andposition of the seam line to be analyzed in a short period of time frominformation displayed by the mark, and enabling a ball positioningoperation centered on the seam line to be smoothly and efficientlycarried out.

The marks and the mark-forming raised or recessed features correspondingthereto in the present invention differ from commonly used markings. Forexample, the markings described in JP-A 10-175219 and JP-A 11-089966 aredisplayed as information for use by the manufacturer, such as the dateof manufacture and the plant where the ball was made. Such markings aregenerally composed of about three letters such as alphanumericcharacters, and are randomly placed on the surface of the ball. Bycontrast, as noted above, the purpose of forming the marks in thepresent invention and the configuration of those marks differ from thosein the prior art.

BRIEF DESCRIPTION OF THE DIAGRAMS

FIG. 1 is a schematic sectional view of a golf ball mold according tothe present invention.

FIG. 2 shows the surface of a golf ball formed with the golf ball moldof the invention.

FIG. 3 shows the relative arrangement of marks when the surface of thegolf ball is viewed from the direction of the seam line.

FIG. 4 shows the relative arrangement of marks when the surface of thegolf ball is viewed from a polar direction.

FIG. 5 is a partial sectional view showing a mark formed in the recessedregion of a dimple.

FIGS. 6(A) and (B) are schematic sectional views showing examples inwhich a mark has a top or bottom face with a shape that follows theshape of a dimple; and FIGS. 6(C) and (D) are schematic sectional viewsshowing examples in which a mark has a top or bottom face with a shapethat does not follow the shape of a dimple.

FIG. 7 shows schematic top views of different types of marks.

FIG. 8 shows schematic perspective views illustrating the shapes ofmarks.

FIG. 9 is an image of the surface of a ball, as taken from above with acamera.

DETAILED DESCRIPTION OF THE INVENTION

The invention is described below in conjunction with the attacheddiagrams.

FIG. 1 is schematic sectional view showing an embodiment of the golfball mold of the invention. The mold has a top half 10 and a bottom half20 which detachably join together so as to form at the interior aspherical cavity 30. The cavity 30 bears numerous dimple-formingprojections 40 on an inside wall 31 thereof. Raised or recessed features50 for forming marks are provided on the cavity wall 31 near the partinglines PL of both mold halves. Elements such as runners, gates, supportpins and vent pins typically disposed around the cavity 30 are omittedin FIG. 1, but the types, numbers and arrangement of such elements maybe treated in the same way as in the prior art.

One distinctive characteristic of the inventive golf ball mold is thepresence of mark-forming raised or recessed features 50. Thesemark-forming features 50 function as indicators for easily detecting theseam line 4 that appears on the surface 1 of the golf ball (molded body)after injection molding with the two-part mold composed of a top halfand a bottom half. Moreover, as shown in FIG. 2, in a golf ball that hasbeen molded using the golf ball mold of the invention, a plurality ofmarks 5 corresponding to the mark-forming features are formed on theball surface 1 on which numerous dimples 3 have been formed. These marks5 are detected and, based on their shapes, the direction and position ofthe seam line 4 are determined.

The number of mark-forming raised or recessed features 50 for each ofthe top half 10 and the bottom half 20 of the mold may be set to atleast one, although it is advantageous for this number to be preferablyat least three but not more than six, and most preferably not more thanfour. It is preferable for these mark-forming features 50 to be disposedat substantially equal intervals on substantially the same latitude.When the ball is inspected from directly above with a CCD or other typeof image processing camera, in order for at least one mark 5 to beidentified and detected regardless of the direction from which the ballis viewed, it is desirable that the mold bear numerous mark-formingraised or recessed features 50 corresponding to the marks 5. However,too many such features 50 may compromise the desirable effects of thedimples 3 on the aerodynamic properties of the ball, and may hinder theefficient removal of the molded object (golf ball) from the mold aftermolding.

Referring to FIG. 3, letting the parting line PL in the spherical cavitywhere the mold halves meet represent the equator (0° latitude), it ispreferable for the mark-forming raised or recessed features 50 to beplaced within a range in the latitude α of from 1° to 45°, and morepreferably from 4° to 30°. By placing the mark-forming features 50 nearthe parting line PL in the cavity 30 within this range, the position ofthe seam line on the ball can be easily determined. The symbol P in FIG.3 indicates the ball polar direction in the spherical cavity.

When a plurality of mark-forming raised or recessed features 50 areplaced on the top half or the bottom half of the mold, as shown in FIG.3, it is desirable for all of the mark-forming features 50 to bedisposed along the same latitude T. This makes the distance between themark-forming features 50 and the seam line 4 uniform, resulting instable precision when identifying and measuring the mark-formingfeatures 50, and also enables positioning of the seam line to be easilyand rapidly carried out.

Moreover, when a plurality of mark-forming raised or recessed features50 are formed on the mold, the relative arrangement of the variousmark-forming features 50 is preferably such that, referring to FIG. 4,the angle of intersection θ between line segments which connect therespective mark-forming features 50 with the center 32 of the sphericalcavity 30 is set to 30° or 60°. This angle θ is the angle on a circledefined by the cavity wall at the mold parting line. For example, inFIG. 4, the relative arrangement of mark-forming features on a top moldhalf 10 as seen from the polar direction is shown as solid lines, andthe relative arrangement of mark-forming features on the bottom moldhalf 20 is shown as dotted lines. Here, three mark-forming features 50 aare arranged at intervals of about 120° on the same latitude of the topmold half 10, and three mark-forming features 50 b are similarlyarranged at intervals of about 120° on the bottom mold half 20. If therespective arrangements of mark-forming features 50 a and 50 b on thetop and bottom mold halves are aligned in the vertical direction, themark-forming features 50 b on the bottom mold half 20 represented bydotted lines in FIG. 4 will be obscured by the mark-forming features 50a in the top mold half 10 represented by solid lines. As a result, whenan image of the ball surface is taken from directly above with a camera,it may be impossible to carry out the rapid detection and identificationof the marks 5 molded on the surface of the ball. Therefore, by havingthe respective arrangements of mark-forming raised or recessed featureson the top and bottom mold halves offset as shown in FIG. 4 by a givenangle of preferably 20° to 40°, and more preferably 25° to 35°, the markdetecting accuracy and mark identifying accuracy are enhanced, making itpossible to rapidly and efficiently determine the direction and positionof the seam line molded on the surface of the ball. That is, when anattempt is made to find the marks on a ball by rotating the ball in onedirection, marks located near the axis of rotation and support aresometimes not recognized. However, if the camera is installed at aposition 90° to the axis of rotation and the field of view is set to30°, even should one mark happen to coincide with the axis of rotation,one or another of the marks on a meridian will inevitably appear withinthe camera's field of view in the course of a single turn about the axisof rotation. As a result, the precision of mark detection can beincreased with a smaller number of marks 5.

The mark-forming raised or recessed features on the cavity wall 31 maybe provided in places on the cavity wall which correspond to lands 2 onthe golf ball, or in places on the cavity wall with correspond todimples. In particular, because the recessed portion of a dimple 3 has arelatively large surface area that is sufficient to accommodate a raisedor recessed feature, it is preferable to provide the mark-formingfeatures 50 on the cavity wall of the mold so that the marks 5 formedthereby are disposed within the recessed portions of dimples. As apreferred mode for placing a mark 5 within the recessed portion of adimple 3, referring to FIG. 5, it is recommended that the mark 5 formedwithin the dimple 3 have a height which does not extend above a lineconnecting the edges E, E of the dimple. If a mark is provided whichprotrudes above the edge E, E of the dimple, part or all of the mark maybe unintentionally removed when the surface of the ball is buffed aftermolding.

It is preferable for the mark 5 to have a shape which follows the shapeof a dimple and/or land area. That is, a mark 5 can have a top faceshape or a bottom face shape which does or does not follow the shape ofa dimple or land area. In the practice of the invention, the mark 5 mayhave any of these shapes. Illustrative examples include cases in which,referring to FIGS. 6(A) and (B), the mark 5 has a top face shape orbottom face shape which follows the shape of a dimple 3, and cases inwhich, referring to FIGS. 6(C) and (D), the mark 5 has a top face shapeor bottom face shape which does not follow the shape of a dimple 3. Ofthese, it is especially preferable for the mark 5 to have a top faceshape or bottom face shape that follows the shape of the dimple 3. Themarks 5 in FIGS. 6(A) and (C) are raised marks which project out fromthe floor of the dimple, and the marks 5 in FIGS. 6(B) and (D) areraised marks which are embedded in the base of the dimple.

The mark-forming raised or recessed features 50 are composed of symbolsfrom which the circumferential direction can be discerned, enabling theposition of the seam line 4 to be determined from the marks 5 molded onthe ball surface 1. It is preferable for such mark-forming features 50to have directional components aligned with the latitude and longitude.Illustrative examples include the symbols shown in FIGS. 7(A) to (E).Generally, when the surface of a golf ball is visually inspected with animage processing camera, if there are numerous alphabetic characters,for example, it takes a while to recognize these, as a result of whichit takes too much time to inspect a large number of golf balls. Bycontrast, in this invention, unlike conventional marks which typicallydisplay product information, the shapes of the marks 5 are recognized ina short time and, based upon information such as the shapes andpositions of the marks 5, the task of determining the direction andlocation of the seam line is rapidly and efficiently carried out.

FIG. 8 shows marks shaped approximately as the letter “T” and an angularletter “U” that have been molded on a surface 1 of a ball. The directionof the seam line on the ball is indicated by shape of the letter interms of latitude (a direction) and longitude (b direction). Thedistance d between the mark 5 and the seam line 4 is from 1.1 to 15.1mm, and preferably from 1.4 to 10.7 mm. The direction of the seam lineis apparent from the shape of such a mark, and the distance of the seamline from the mark can be determined from this mark information.

The mark-forming raised or recessed features 50, while not subject toany particular size limitation, typically have a size, expressed as thelength by width of the shape, which is preferably not more than 4.0 by4.0 mm, more preferably not more than 3.0 by 3.0 mm, and even morepreferably not more than 2.0 by 2.0 mm. When the mark-forming features50 are provided with a raised shape, the raised shape has a height (h inFIG. 7) which, while not subject to any particular limitation, ispreferably from 5 to 200 μm, more preferably from 10 to 100 μm, and evenmore preferably from 20 to 50 μm. On the other hand, when themark-forming features 50 are provided with a recessed shape, therecessed shape has a depth which, while not subject to any particularlimitation, is preferably from 5 to 200 μm, more preferably from 10 to100 μm, and even more preferably from 20 to 50 μm. The height and depthsettings of these mark-forming features 50, regardless of whether thefeatures 50 are raised or recessed, may be adjusted as appropriate solong as the mark-forming features 50 provided on the cavity wall 31 donot catch, thereby preventing the golf ball from being easily removedfrom the mold cavity after injection molding.

FIG. 9 is a plan view showing the surface of the ball as captured with acamera after the ball has been turned through a given angle and arrangedwith the seam line 4 at the center; that is, after the ball positioningoperation has been carried out. The vertical line at the center of thisimage frame F is the seam line 4, and the symbol O is the center of thecaptured image.

The method used to form the above-described mark-forming raised orrecessed features in the mold is not subject to any particularlimitation. In one exemplary method, mark-forming recessed featuresand/or raised features are formed on a cavity wall 31 where numerousdimple-forming projections have been formed. In another method, first amaster mold provided with numerous recessed features capable of formingdimple-forming projections is fabricated, following which the desiredmark shapes are machined into the surface shape of the master mold, thenthe pattern in the master mold is reversed so as to form a golf ballmold having the desired surface shape on the cavity wall. To fabricatesuch a mold, a technique may be employed in which, as is commonplace inthe art, 3D CAD/CAM is used to directly cut the entire surface shapethree-dimensionally into a master mold from which the golf ball mold issubsequently made by pattern reversal, or to directly cutthree-dimensionally the cavity wall for the golf ball mold.

The golf ball of the invention is one which, as noted above, has beenmolded from the golf ball mold of the present invention. As shown inFIG. 2, numerous dimples 3 are formed on the surface 1 of the ball, inaddition to which marks 5 which correspond to the above-describedmark-forming raised or recessed features 50 are formed on land areas 2and/or within dimples 3. These marks 5 are arranged on the surface ofthe ball based on the relative arrangement of the above-describedplurality of mark-forming features 50.

Although not illustrated in the diagrams, it is preferable for indiciasuch as lettering, trade marks and designs to be applied on the seamline of the inventive golf ball. It is therefore advantageous for theindicia applied on the seam line of the ball to be of a size such thatthe dimension thereof in the direction of the seam is preferably atleast five times, and more preferably at least ten times, the dimensionin the direction orthogonal thereto (i.e., the longitudinal direction).More specifically, the length in the seam direction is preferably atleast 15 mm.

As explained above, the marks 5 formed on the surface 1 of the golf ballare effectively employed in subsequent steps, such as the application ofindicia to the surface of the ball and the positioning of the ball forvisual inspection. That is, the marks 5 that have been formed on thesurface 1 of the ball are identified—typically with an image processingcamera and, based on the shape of those marks 5, the direction andposition of the seam line on the ball can be determined. A ballpositioning operation is then smoothly carried out by using, forexample, an orienting means to rotate the ball a specific amount so asto position the seam line in the center.

In the practice of the invention, the core of the golf ball is notsubject to any particular limitation. Use can be made of any of avariety of cores, such as a single-layer solid core, a solid core havinga plurality of vulcanized rubber layers, a solid core having a pluralityof resin layers, or a thread-wound core having a rubber thread layer. Inaddition, a cover layer can be formed over the above core. The materialmaking up this cover layer is preferably a known thermoplastic resin orthermoplastic elastomer composed primarily of ionomer resin or urethaneresin. The cover is not limited to one layer, and may be formed so as tohave a multilayer construction of two or more layers. The coverthickness (per layer) may be selected as appropriate for the diameter ofthe core and the number of cover layers, although the thickness percover layer is generally from 0.5 to 3.0 mm.

The types and shapes of the numerous dimples 3 formed on the surface 1of the ball are not subject to any particular limitation, although it ispreferable to select circular or non-circular dimples of the same ordifferent types which have a diameter in a range of 1 to 6 mm and adepth of 0.05 to 0.4 mm. These dimples may be arranged on the surface ofthe ball in any of various patterns, such as a regular dodecahedral,regular icosahedral or regular octahedral arrangement.

The golf ball of the invention is preferably formed to a diameter andweight in accordance with the Rules of Golf, and typically has adiameter of not less than 42.67 mm and a weight of not more than 45.93g.

Some preferred embodiments of the invention have been described above indetail with reference made to the attached drawings. However, the golfball and golf ball mold of the invention are not limited to thesedrawings and embodiments, and various modifications may be made theretowithout departing from the gist of the invention. For example, thearrangement, number and shape of the mark-forming raised or recessedfeatures are not limited to those specific in the foregoing embodimentsand drawings, and may be suitably modified and selected withoutdeparting from the spirit and scope of the invention as disclosed in theaccompanying claims.

The golf ball and golf ball mold of the invention help to significantlyshorten the work time and improve efficiency by enabling the directionand position of the seam line on the surface of the ball to be easilyidentified, and by making it possible to more smoothly andadvantageously carry out subsequent operations such as visual inspectionof the ball and the application of indicia to the surface of the ball.

1. A golf ball mold comprising a top half and a bottom half that detachably join together so as to form therein a spherical cavity into which a material is injected to mold a golf ball, which mold bears, near a parting line between the top and bottom halves on a wall of the cavity, a raised or recessed feature for forming a mark as an indicator for detecting the direction or position of the parting line.
 2. The golf ball mold of claim 1 which has at least one mark-forming raised or recessed feature on each of the top and bottom halves of the mold.
 3. The golf ball mold of claim 1 wherein, if the parting line in the spherical cavity where the mold halves meet represents 0° latitude, the mark-forming raised or recessed feature is disposed on the cavity wall within a range in latitude of 1° to 45°.
 4. The golf ball mold of claim 1 wherein mark-forming raised or recessed features formed on the respective mold halves are disposed so as to be substantially equally spaced apart relative to an axis of rotation circumscribed by the parting line of the mold.
 5. The golf ball mold of claim 1 wherein mark-forming raised or recessed features on the top half exist in a relative arrangement with mark-forming raised or recessed features on the bottom half such as to be separated therefrom at a given angle of about 20° to 40° relative to an axis of rotation circumscribed by the seam line.
 6. The golf ball mold of claim 1 wherein the cavity wall bears numerous dimple-forming projections, which projections have on a surface thereof a mark-forming raised or recessed feature that is recessed.
 7. The golf ball mold of claim 1, wherein the mark-forming raised or recessed feature comprises one simple symbol or letter.
 8. The golf ball mold of claim 1, wherein the mark-forming raised or recessed feature has a size of at most 4.0 mm by 4.0 mm.
 9. The golf ball mold of claim 1, wherein the mark-forming raised or recessed feature has a height or depth of 5 to 200 μm. 